Recent work in the field of silver halide color photographic materials has been directed at development of materials having super-high sensitivity as typically illustrated by ISO 1,600 films, with excellent image quality and sharpness suitable for use in small format cameras such as the 110 size cameras and disc cameras.
In order to improve sharpness, the thickness of the photographic light-sensitive material may be reduced resulting in a reduction of the optial scattering path during exposure and a reduction in the diffusion path of the oxidation product of developing agents formed at development. In order to reduce thickness, the amount of the binder employed such as gelatin must be decreased. However, when thickness is reduced in this manner, oil droplets tend to sweat on the surface or within other layers of the photographic material when stored under conditions of high temperature and high humidity before or after processing and images thus formed also fade, as described in JP-A-59-l48052, and JP-A-59-l49347 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
A method of reducing the thickness of an emulsion layer using .a polymer coupler instead of an oil-protected type coupler is described in JP-B-44-l3375 (the term "JP-B" as used herein means an "examined Japanese patent publication"), JP-A-52-l5063l and U.S. Pat. No. 3,370,952. However, the color forming property of a coupler is decreased by polymerization thus requiring an even thicker emulsion layer.
Moreover, in order to reduce molecular weight per color forming unit, yellow couplers having two to four color forming units per molecule are described in JP-A-53-82332, JP-A-54-l33329, JP-A-55-2300 and JP-A-56-92539. However, these couplers also have low color forming properties.